DAF CF65, CF75, CF85 Series . Manual - part 1085

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General

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1. GENERAL

1.1 REPAIRS TO THE CHASSIS

-

Any welding, aligning, drilling and wheelbase 

alteration activities that are not described in 

this workshop manual or in any of the latest 

releases of DAF's Chassis Guidelines must 

be authorised by DAF.

-

Following chassis repair, the cause of the 

chassis damage should be rectified.

Welding
-

Chassis welding may only be carried out by 

welders holding a valid EN 287-1 certificate.

-

For welding operations on the steel grade KF 

375 chassis, the welding electrode must 

meet one of the following standards:

-

Slag inclusions and other contamination in 

the welds are totally unacceptable.

Note:

Welding on a chassis constructed of high-tensile 

strength steel grades KF 420, KF 500 and KF 600 

is strongly advised against.

If, however, you do wish to weld a high-tensile 

strength steel chassis, contact must always first 

be sought with DAF.

The welding electrode must meet the standard:

ISO 2560:

E 515 B 24(H)

DIN 1913 (January 1976): E 5155 B 10
EN 499

DIN 8529:

EY 5066 1.5 NiNoB

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To repair cracks in the chassis, proceed as 

follows, taking account of the guidelines given 

above:

1.

Remove all parts restricting a clear working 

area.

2.

Thoroughly clean the crack so that the 

course of the crack is clearly visible.

3.

Drill a small hole at the end of the crack. This 

will prevent the crack from continuing.

4.

Thoroughly grind out the crack on both sides.

5.

Take the necessary precautions to prevent 

damage to electronic components. Place the 

earth clamp as close as possible to the weld 

and avoid bridges.

6.

Lay a bead on one side of the ground-out 

crack.

7.

Gouge or grind off the material at the back of 

the bead (see the arrow) so that the new 

weld material is clearly visible.

8.

Finish-weld the X-seam in the usual manner.

9.

Fill in the drilled hole.

10. Grind down the new weld so that it is flush. 

Take care not to grind the chassis flange in 

the process.

11. The beginning and end of a weld should not 

curve inwards (see the arrow).

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12. Round off the chassis flange at the edge of 

the weld.

Straightening

Do not forget your own safety during 

straightening operations. When 

working with presses, take care that 

parts cannot fly out.

The straightening of a chassis demands a high 

degree of craftsmanship as in every case of 

damage, an individual assessment must be made 

to establish whether or not straightening would be 

a sensible measure.

Deformations found after accidents will mainly be 

of the following 6 types:

-

chassis is bent sideways

-

chassis has a double sideways bend ("S-

bend")

-

chassis sags

-

chassis bulges upwards

-

chassis is twisted

-

chassis is out of square.

In many cases, the damage will be a combination 

of two or more of these basic deformations.

In general, the deformations should be dealt with 

in the sequence shown above, although some 

combinations can be dealt with in one 

straightening operation.

When deciding whether or not to straighten a 

chassis, you must consider not only the degree of 

chassis bending but also the angle of a bend.

If there is a sharp angular bend or fold in the 

chassis, the material in that area is likely to be 

severely deformed.

If such a chassis were to be realigned to its 

original form, there would be a high risk of 

overstretching the already weakened material 

and causing a crack to develop.

"Cold" straightening
The general rule for cold straightening of a 

chassis is that the degree to which the chassis 

should be forced back beyond the straight line is 

equal to the degree to which the chassis is bent. 

For example, if a chassis is bent by 10

, the 

chassis should be forced back by an additional 

10

 beyond the straight line.

This means that in total the chassis is forced back 

20

.

Cold straightening is done with forces ranging 

from 40 to 100 tonnes. Therefore, work as safely 

as possible.

Particularly when working with auxiliary tools and 

aids, you are advised - from a safety point of view 

- to attach them correctly.

100mm

R=1

R=1

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"Warm" straightening
DAF chassis should not be warm straightened. 

Heating can cause grains in the material which 

will adversely affect the material properties.

General
For every straightening operation, all stresses in 

the stiffer parts of the chassis, for example in the 

tandem axle attachment cross member, should 

be relieved. If this is not done, these stresses will 

later cause new distortions or cracks in the 

chassis.

It is obvious from the above points that 

straightening is a highly specialised job for which 

the specialist involved bears full responsibility. 

Always contact DAF when in doubt or for 

complicated "straightening operations".